Method for determining the position of a vehicle

ABSTRACT

A computer implemented method for determining the position of a vehicle, wherein the method comprises: determining at least one scan comprising a plurality of detection points, wherein each detection point is evaluated from a signal received at the at least one sensor and representing a location in the vehicle environment; determining, from a database, a predefined map, wherein the map comprises a plurality of elements in a map environment, each of the elements representing a respective one of a plurality of static landmarks in the vehicle environment, and the map environment representing the vehicle environment; matching the plurality of detection points and the plurality of elements of the map; determining the position of the vehicle based on the matching; wherein the predefined map further comprises a spatial assignment of a plurality of parts of the map environment to the plurality of elements, and wherein the spatial assignment is used for the matching.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application Number19212492.3, filed Nov. 29, 2019, the disclosure of which is incorporatedby reference in its entirety herein.

TECHNICAL FIELD

The present disclosure relates to a computer implemented method fordetermining the position of a vehicle.

BACKGROUND

A method for determining the position of a vehicle can be provided for avehicle which is equipped with a sensor system, wherein the sensorsystem includes at least one sensor for receiving electromagneticradiation emitted from at least one emitter of the sensor system andreflected in a vehicle environment towards the at least one sensor. Themethod comprises: determining at least one scan comprising a pluralityof detection points, wherein each detection point is evaluated fromelectromagnetic radiation received by the at least one sensor andrepresenting a location in the vehicle environment; determining, from adatabase, a predefined map, wherein the map comprises a plurality ofelements in a map environment, each of the elements representing arespective one of a plurality of static landmarks in the vehicleenvironment, and the map environment representing the vehicleenvironment; matching the plurality of detection points and theplurality of elements of the predefined map; determining the position ofthe vehicle based on the matching.

Self-localization or ego-localization of a vehicle with respect to apredefined map such as a navigation map is an important task in thefield of autonomous driving and similar applications. On-board radarsystems are able to detect objects like buildings, trees, poles andother vehicles—even under bad weather conditions.

The radar detections acquired by a radar system (or other detectionpoints) can be used to localize the vehicle within the navigation map.The navigation map can be gathered from a publicly available database.For example, it can be a so called “OpenStreetMap”. Alternatively, thenavigation map can be provided by a commercial map provider. Such mapsusually are particularly accurate. Generally, the navigation map can bederived from a global database on the basis of a given position of thevehicle, e.g. from a global position system of the vehicle.Alternatively, a preliminary position estimate can be determined usingodometry.

The static landmarks can be known static objects, i.e. infrastructuralobjects or persistent objects, like walls of buildings, barriers,fences, pavement edges, poles, bigger plants, trees and the like. Themap data stored in the database comprise simplified mathematicalrepresentations of the landmarks, for example in the form of extendedgeometrical objects like lines. Each of the elements comprisesinformation about its position in a world coordinate system.

The term “matching” can be understood in the sense of evaluating acorrespondence between the radar detection points and the elements ofthe map. To carry out the matching, a so called Scan Matching algorithmcan be applied. An example of a Scan Matching algorithm is disclosed inEP 3 517 996 A1. In the context of Scan Matching, the correspondencebetween the detection points and the elements of the map is exploitedfor the determination of the position of the vehicle.

Although the methods can use a radar system of a vehicle, it isunderstood that the methods may also be adopted using detection pointsof a LiDAR system instead of a radar system. Combinations of radar andLiDAR detection points may also be possible.

For the matching, every scan of a current set of (e.g. radar) scans canbe projected into the closest map element (Building/wall). The closestmap element has to be identified before the projection. If the scanmatching algorithm is executed in a more complex environment within alarge area, e.g. a whole city, consisting of more buildings/walls orapplied for every radar scan recursively/circularly the computationaleffort increases and a more sophisticated approach for calculating themap projection is needed.

Therefore, a problem associated with the matching is the highcomputational load. Accordingly, there is a need to provide a moreefficient method for determining the position of a vehicle.

SUMMARY

The present disclosure provides a computer implemented method, acomputer system and a non-transitory computer readable medium accordingto the independent claims. Embodiments are given in the subclaims, thedescription and the drawings.

In one aspect, the present disclosure is directed at a computerimplemented method for determining the position of a vehicle equippedwith a sensor system, wherein the sensor system includes at least onesensor for receiving electromagnetic radiation emitted from at least oneemitter of the sensor system and reflected in a vehicle environmenttowards the at least one sensor, wherein the method comprises: capturingat least one scan comprising a plurality of detection points, whereineach detection point is evaluated from electromagnetic radiationreceived by the at least one sensor and representing a location in thevehicle environment; determining, from a database, a predefined map,wherein the map comprises a plurality of elements in a map environment,each of the elements representing a respective one of a plurality ofstatic landmarks in the vehicle environment, and the map environmentrepresenting the vehicle environment; matching the plurality ofdetection points and the plurality of elements of the map; determiningthe position of the vehicle based on the matching; wherein thepredefined map further comprises a spatial assignment of a plurality ofparts of the map environment to the plurality of elements, and whereinthe spatial assignment is used for the matching.

The parts are defined by spatial positions arranged as a mesh grid whichcomprise the positions for any potential detection point.

The spatial assignment allows for a more efficient assignment betweenthe detection points and the elements. This means that for assigning agiven detection point to one or more of the elements it is not necessaryto carry out an exhaustive search through the elements, for example inorder to find the nearest element for the given detection point.Instead, the spatial assignment readily gives the information to whichelement a given detection point is assigned. In this regard, the spatialassignment can be regarded as an additional layer of the map, which ispre-computed, i.e. predetermined so that complex assignment steps can beavoided during runtime of the method. The method therefore enables aparticularly efficient self-localization of vehicles within any kind ofenvironment and in particular in urban environments. In experiments, ithas been found that the proposed method outperforms conventional scanmatching algorithms by 35 percent in time.

It is understood that the emitter of the sensor system can emitelectromagnetic radiation during determining the one or more scans. Inone example, the sensor system can be a radar sensor system and thedetection points can be radar detection points.

The matching comprises: identifying, for a respective one of theplurality of detection points, a respective one of the plurality ofparts of the map environment, the respective one of the plurality ofparts of the map environment representing a part of the vehicleenvironment including the location represented by the respective one ofthe plurality of detection points; identifying a respective one of theplurality of elements being assigned to the identified respective one ofthe plurality of parts of the map environment; assigning the identifiedrespective one of the plurality of elements to the respective one of theplurality of detection points. These steps can be carried out for all orsome of the plurality of detection points. It is understood that thesesteps can be carried out with low computational load because thepredefined map already comprises the spatial assignment. Particularly,the assignment of the element to the detection point is carried out onthe basis of the spatial assignment. This assignment can be fullypredetermined by the spatial assignment of the map.

A mixed mode of predetermining the spatial segments with more than oneof said methods can be used to avoid the calculation of the distanceduring algorithm execution time.

It is generally understood that a part of the map environment ispreferably assigned to only one single element of the map. However, itis possible that a part of the map environment is assigned to more thanone element. This may be useful for partially overlapping elements. Forexample, a corner point can be the end point of two connected lines,wherein the lines form elements of the map.

Advantageous embodiments of the invention are specified in the dependentclaims, in the description and in the appended drawings.

According to an embodiment, the predefined map comprises a definition ofa plurality of spatial segments, each of the spatial segmentsrepresenting a part of the map environment and being assigned to arespective one of the plurality of elements. The spatial segments can beconfigured as so-called Voronoi segments or cells. The Voronoi segmentsform a Voronoi diagram, which can be used as an additional layer of themap. In general, a Voronoi diagram is a partition into regions ofdetection points, which have the closest distance to a respectiveelement from all elements of the map (e.g., points or lines). It cangive a probability for assignment of a detection point to its nearestmap element. The distance between the detection point and itscorresponding map element can be given by a distance metric, e.g.Euclidian distance.

The spatial segments can be defined in different ways, for example by anumber of (discrete) positions forming a grid, for example like pixelsof an image. The positions are structured in groups, wherein eachposition of a respective group has the same assignment to one or moreelements of the map. Hence, a spatial segment is formed. Alternativelyor additionally, the spatial segments can be defined by corner points ofthe spatial segments, wherein the corner points are connected byboundary lines of the segments. Further and similar approaches fordefining and determining the spatial segments can be found in thefollowing publication: Burnikel, Christoph, Kurt Mehlhorn, and StefanSchirra: “How to compute the Voronoi diagram of line segments:Theoretical and experimental results.” European Symposium on Algorithms.Springer, Berlin, Heidelberg, 1994.

One way to determine the spatial segments is to discretize the mapelements (e.g., lines). Fortune's algorithm can then be used tocalculate the Voronoi cells on points created on the elements (e.g.,line segments) to calculate the line assignment beforehand. For thisaim, the Voronoi cells intersected by the same line are joined. Finally,all boundary indices of the line segment Voronoi cells are stored andcan be evaluated during the scan matching algorithm by checking whichpolygon (i.e. spatial segment) a detection point is assigned to. Thismethod has the advantage to provide very accurate spatial segmentboundaries (i.e. Voronoi cell boundaries).

According to an embodiment, the matching is carried out on the basis ofidentified respective ones of the plurality of elements and respectiveones of the plurality of detection points to which the identifiedrespective ones of the plurality of elements have been assigned. Theassignment can be solely based on the spatial assignment, i.e. theelement being assigned to the part of the map, which comprises a givendetection, is also assigned to the given detection point. However, it ispossible to incorporate further rules, for example that an assignment ofan element to a given detection point requires that the distance betweenthe element and the given detection point is below a predefinedthreshold. In this way, noisy detection points can be filtered so thatthey do not influence the matching.

According to an embodiment, the method comprises determining at leastone confidence value for a respective one of the plurality of detectionpoints on the basis of the spatial assignment, wherein the at least oneconfidence value represents a probability that the respective one of theplurality of detection points is assigned to a respective one of theplurality of elements, and wherein the matching is carried out on thebasis of the at least one confidence value. In other words, detectionpoints can be matched to one or more elements in dependence of aconfidence value. In one example, a plurality of confidence values canbe determined for a respective detection point, each of the confidencevalues representing the probability that the respective detection pointis assigned to a respective one of the plurality of elements.

According to an embodiment, the at least one confidence value isdetermined on the basis of a Monte-Carlo simulation for the respectiveone of the plurality of detection points. This can be done one the basisof pose uncertainties (e.g., standard deviation of position and headingof the preliminary position of the vehicle) and/or detection pointuncertainties (e.g., standard deviation in angle and range for a radardetection point).

According to an embodiment, the at least one confidence value istransformed to an exponential weighting factor and wherein the matchingcomprises weighting by the exponential weighting factor. The exponentialweighting is effective to focus on major influences and to alleviateeffects of outliers. However, other weighting schemes are also possible.

According to an embodiment, the predefined map further comprises aplurality of distance values representing distances between theplurality of parts of the map environment being assigned to theplurality of elements and the elements, respectively. The distancevalues can be used for the matching in order to further increase theefficiency of the method. The distances can be defined as Euclidiandistances. The parts can be defined by spatial segments, as indicatedfurther above.

According to an embodiment, the spatial assignment identifies, for arespective one of the plurality of parts of the map environment, arespective one of the plurality of elements having a minimum distance tothe respective one of the plurality of parts of the map environment.Accordingly, each of the distances of the map can be a minimum distance,for example defined by the orthogonal projection of the detection pointonto the element. In one example, the element can be a line, so thedetection point is projected onto the line.

According to an embodiment, the matching comprises determining a rigidtransformation function by minimizing distances between transformeddetection points and elements being assigned to the plurality oftransformed detection points by means of the spatial assignment, whereinthe transformed detection points are respective ones of the plurality ofdetections points transformed by means of the rigid transformationfunction.

According to an embodiment, the at least one element of the mapcomprises an extended geometrical object, in particular a line or asurface, preferably a straight line or a plane. In one example, theelements are formed by lines, wherein each of the lines is defined toextent between two spatially defined end points of the lines. The linecan be a vector between two end points.

According to an embodiment, the matching comprises particle filtering. Aparticle filter is powerful for global self-localization of the vehicle.Because of the high computational burden for particle filtering usingthe proposed spatial assignment of the map significantly reduces thecomputational load. For global self-localization using particlefiltering the weighting process can be computationally intensive. Forweight calculation, the particle is projected into the map based on theangle of every detection point. The distance between the particle andits projection is compared to the detection range. In one example, themap can be a parking lot map, wherein the initialization (finding theinitial pose of the vehicle) requires a distribution of ≈30000particles. Considering this number of particles and the number ofdetection points up to 128 detection points for each radar scan, theweighting process can hardly be performed in an acceptable time for realtime applications. Applying the spatial assignment for the assignmentsand distance calculation reduces the computational time considerably(tests have shown a reduction in time by 99 percent). This considerablecomputation time reduction allows further real-time capable developmentsof global self-localization based on particle filtering, particularlywhen the area of the unknown initial pose becomes smaller (not as largeas the whole parking lot).

According to an embodiment, the method further comprises determining apreliminary position of the vehicle, and wherein determining theposition of the vehicle comprises transforming the preliminary positionby means of the rigid transformation function.

According to an embodiment, the method further comprises determining theposition, in particular the preliminary position, on the basis of amotion model of the vehicle, wherein the motion model is determined onthe basis of at least one measurement from at least one motion sensor ofthe vehicle and/or on the basis of at least some of the plurality ofdetection points of the at least one scan. The motion model can be amodel which describes the trajectory of the vehicle over time. The modelcan be initialized with some value and is then periodically updatedbased on motion measurements of the vehicle. In this regard, the motionmodel is preferably determined on the basis of at least one measurementfrom at least one motion sensor of the vehicle and/or on the basis of atleast some of the detection points. The combination of measurements froma motion sensor and a radar system can further enhance the accuracy ofthe method. As an alternative to using a motion model a suitablelocalization system can be used, for example on the basis of a DGPS(Differential Global Positioning System).

The measurement from the at least one motion sensor can comprise avelocity and/or a yaw rate of the vehicle, wherein the vehiclepreferably comprises corresponding sensor facilities. This is also knownas “dead-reckoning” measurements. Preferably, the velocity and/or theyaw rate of the vehicle is determined on the basis of wheel-speed-sensor(wheel rotation per time span) measurements and/or yaw-rate-sensormeasurements. Dead-reckoning measurements taken alone have been found toprovide inaccurate estimations of the vehicle position under certainconditions, e.g., during strong steering maneuvers. For this reason, theestimation based on dead-reckoning can represent a preliminaryestimation of the vehicle's position.

The position of the vehicle can comprise coordinates representing alocation and an orientation of the vehicle.

In another aspect, the present disclosure is directed at a computersystem, said computer system being configured to carry out several orall steps of the computer implemented method described herein. Thecomputer system can be connected or connectable to a sensor or sensorsystem of a vehicle, wherein the sensor or sensor system can beconfigured to perform at least the method step of determining the atleast one scan. The sensor can be part of a sensor unit, which can be aradar sensor unit or a LiDAR sensor unit.

The computer system can be configured to perform other method stepsdisclosed herein, in particular determining the predefined map,transforming the map, matching and/or determining the position. Relatedmethod steps can also be performed by the computer system. The computersystem can also be connected or connectable to motion sensors of thevehicle or to a localization system in order to determine a preliminaryposition of the vehicle, for example by using a motion model of thevehicle. The computer system can be formed or can be part of a computingunit or system of the vehicle, for example an electronic control unit(ECU) of the vehicle.

The computer system may comprise a processing unit, at least one memoryunit and at least one non-transitory data storage. The non-transitorydata storage and/or the memory unit may comprise a computer program forinstructing the computer to perform several or all steps or aspects ofthe computer implemented method described herein. The non-transitorydata storage and/or the memory unit may comprise a data base in whichmap data for determining the predefined map is stored.

In another aspect, the present disclosure is directed at a vehicleequipped with a sensor system adapted to receive electromagneticradiation emitted from at least one emitter of the sensor system andreflected in a vehicle environment towards the sensor system, and acomputer system for determining a position of the vehicle on the basisof the emitted and the reflected radiation.

In another aspect, the present disclosure is directed at anon-transitory computer readable medium comprising instructions forcarrying out several or all steps or aspects of the computer implementedmethod described herein. The computer readable medium may be configuredas: an optical medium, such as a compact disc (CD) or a digitalversatile disk (DVD); a magnetic medium, such as a hard disk drive(HDD); a solid state drive (SSD); a read only memory (ROM), such as aflash memory; or the like. Furthermore, the computer readable medium maybe configured as a data storage that is accessible via a dataconnection, such as an internet connection. The computer readable mediummay, for example, be an online data repository or a cloud storage.

The present disclosure is also directed at a computer program forinstructing a computer to perform several or all steps or aspects of thecomputer implemented method described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments and functions of the present disclosure aredescribed herein in conjunction with the following drawings, showingschematically:

FIG. 1 a block diagram of method for determining the position of avehicle;

FIG. 2 distances between exemplary detection points and a line beingassigned to the detection points;

FIG. 3 mathematical expressions for determining the distances from FIG.2 and for determining a rigid transformation function;

FIG. 4 exemplary spatial segments assigned to lines of a map;

FIG. 5 the spatial segments from FIG. 2 as a line drawing;

FIG. 6 a portion of the map from FIG. 4 comprising the lines of the map;a portion of the map with spatial segments assigned to the lines, and aportion of the map representing distance values between the mapenvironment and the lines;

FIG. 7 portions of the map with spatial segments assigned to lines andwith a plurality of samples for a given detection point.

DETAILED DESCRIPTION

FIG. 1 depicts a block diagram of a method for determining the positionof a vehicle. The method can be carried out by a computer system of thevehicle (not shown). In block 10, a plurality of scans are determined,each of the scans comprising a plurality of detection points. In block12, a predefined map is determined from a database, wherein the mapcomprises a plurality of elements, each of the elements representing astatic landmark. The database is stored in a non-transitory storagemedium of the computer system. In the following, the elements of the mapare assumed to be formed by lines. However, other types of elements arealso possible.

The database comprises map data for a large area, wherein the map isdetermined by taking a portion of the map data, which corresponds to apreliminary position of the vehicle. In other words, the map compriseslines in a map environment, which corresponds to a current vehicleenvironment. The map also comprises a spatial assignment of parts of themap environment to the elements of the map. Particularly, the mapenvironment is represented by a plurality of positions (e.g. a grid),wherein each of the positions is assigned a line of the map. Thepositions are potential positions of detection points of the scans. Themap further comprises a distance value for each of the positions. Thedistance values give the minimum distance between the positions and theassigned lines, respectively. This will be described further withrespect to FIG. 2 and FIG. 3.

In block 14, matching is carried out between the detection points andthe elements of the map. The spatial assignment of the predefined map isused for the matching and allows for carrying out the matching with highefficiency. For a given detection point the corresponding position inthe map environment is identified, which can comprise one or morerounding operations of one or more coordinates of the detection point tocoordinates of the nearest position in the map environment. Other waysof identifying the position are also possible. On the basis of thespatial assignment the element being assigned to the position is alsoassigned to the detection point. No exhaustive search through allelements of the map is necessary. Instead, the nearest element for agiven detection point can readily be identified using the spatialassignment, which is part of the predetermined map.

In block 16, the current position of vehicle is determined on the basisof the matching. This can comprise updating the preliminary positionwith information from the matching, in particular a rigid transformationfunction.

FIG. 2 shows two exemplary detection points P and P′, which are assignedto an element 18 of the map. The element 18 is considered to be thenearest element for both detection points P and P′. The element 18 is aline segment S, which extends between a first endpoint L_(min) (i.e.startpoint) and a second endpoint L_(max). The distance between thedetection point P and the line S is the Euclidean distance d(P), whichis the minimum distance between P and S (orthogonal projection). For thedetection point P′, the minimum distance is d(P′), as shown in FIG. 2,which is the distance between P′ and the end or corner point L_(max). Ingeneral, the minimum distance calculation can be expressed by formula 20shown in FIG. 3. The first case of formula 20 describes the orthogonalprojection, as for detection point Pin FIG. 2. The second case offormula 20 describes the minimum distance to one of the endpoints, asfor the detection point P′ in FIG. 2.

Formula 20 is used to compute a spatial assignment between parts of themap and the elements of the map, for example the element 18. The resultis shown in FIG. 4, which shows an exemplary map 24 comprising aplurality of elements, for example element 18, in a map environment 26.The map environment 26 is divided into spatial segments 28, which areshown in different grey scales in FIG. 4 and which form parts of the mapenvironment 26. The spatial segments are shown without grey scales inFIG. 5, see segments 28 and 28′ for example. The spatial segments areassigned to the lines in the map environment 26, respectively. Forexample, the spatial segment 28 is assigned to line 18, which is theline with the minimum distance to all points within the spatial segment28. The spatial segments 28 can be determined offline (e.g. beforecarrying out the method described in FIG. 1) on the basis of a regulargrid of positions covering the map environment 26. For each positionformula 20 is used to determine the minimum distance to all of the lines(i.e. elements) in the map environment 26. The minimum from all distancevalues for all of the lines is than selected and the respective line isassigned to the respective position. In this way, a spatial assignmentis computed for each point of the grid, i.e. each position is assignedto the nearest line. The spatial assignment is stored as a look-up tableas an additional layer of the map 24. Additionally, the correspondingdistance value is stored for each of the positions as another additionallayer of the map. During run time, see blocks 10, 12, and 14 in FIG. 1,the map is evaluated for each of the detection points. For example, if agiven detection point P is located inside the spatial segment 28, theline 18 is readily determined as the nearest line from all lines of themap by using the spatial assignment of the map. Additionally, thedistance value d is known from the map. Matching can then be carried outbetween detection points and the assigned lines, wherein the overallmatching process is very efficient due to the spatial assignment and thedistance values, which forms precomputed data.

The matching 14 comprises determining a rigid transformation function byminimizing the expression 22 of FIG. 3. Expression 22 is a double sumover N lines of the map and M detection points di. This corresponds to aleast squares estimator for rotation R and translation t, wherein thej-th line is parameterized by the normal vector n_(j) and the orthogonaldistance b_(j) between the j-th line and the origin. The expressionf(p_(ij)) denotes an exponential weighting factor for the matching anddepends on the probability p_(ij) of detection point di being assignedto the j-th line. This is done by performing a Monte-Carlo simulationincorporating current pose uncertainties (position and heading or thepreliminary position of the vehicle) and the detection pointuncertainties, e.g. standard deviation in angle and range for a radardetection point. The propagated error ellipse (mean and standarddeviation) as distribution (Gaussian) for K randomly generated samples(inputs) for each detection point is considered. First, the samples areassigned to one or more lines by using the spatial assignment. For eachline, the number of assignments from the samples is counted. Theprobability p_(ij) is then calculated as the ratio between the number ofassignments to the j-th line and the total amount of samples (inputs) Kfor the i-th detection point. The weighting factor can be used insteadof a hard 0-1 assignment from the spatial assignment. This leads to animproved accuracy of the matching and hence to an improved accuracy ofthe determined position. The generation of K samples is illustrated inFIG. 7 showing the map portion 32′, which corresponds to the map portion32 from FIG. 6 discussed further below. A point cloud 38 is shown in thefigure and represents K random samples drawn from the distribution. Thedistribution is represented by a propagated Gaussian error ellipse 40.An enlarged portion 36 is also shown in FIG. 7. It is understood that byusing the spatial assignment the samples 38 will be assigned todifferent lines because the samples 38 are located in different spatialsegments. In this way, the probabilities p_(ij) can be determined asdescribed.

FIG. 6 shows a portion 30 of the map 24 with lines of the map 24, forexample line 18. The lines represent the walls of a parking garagelevel. The portion 30 can also be regarded as the map 24, wherein thespatial assignment is an additional layer or portion of this map.Another portion 32 of the map 24 is shown in FIG. 6, which correspondsto the map 24 of FIG. 4 with colored spatial segments but without thelines. FIG. 6 includes another portion 34 of the map 24 representingdistance values between the map environment 26 and the lines as colorintensity, i.e. for a given point in the map portion 34 the colorintensity indicates the distance to the nearest line according toformula 20. The distance values form another additional layer of the map24.

What is claimed is:
 1. A method comprising: receiving, from anelectromagnetic system with at least one sensor equipped on a vehicle,electromagnetic radiation emitted by the electromagnetic system andreflected in a vehicle environment towards the at least one sensor;determining, based on the electromagnetic radiation, at least one scancomprising a plurality of detection points (P), each detection pointrepresenting a location in the vehicle environment; determining, from adatabase, a predefined map comprising: a plurality of elements in a mapenvironment, each of the elements representing a respective one of aplurality of static landmarks in the vehicle environment; and a spatialassignment of a plurality of parts of the map environment to theplurality of elements, the plurality of parts being spatial positionsarranged as a mesh grid comprising positions for any potential detectionpoint, at least a portion of the map environment representing thevehicle environment; matching, using the spatial assignment, theplurality of detection points (P) to the plurality of elements in themap environment, by at least: identifying, for a respective one of theplurality of detection points (P), a respective one of the plurality ofparts of the map environment, the respective one of the plurality ofparts of the map environment representing a part of the vehicleenvironment including the location represented by the respective one ofthe plurality of detection points; identifying a respective one of theplurality of elements being assigned to the identified respective one ofthe plurality of parts of the map environment; and assigning theidentified respective one of the plurality of elements to the respectiveone of the plurality of detection points (P); determining the positionof the vehicle based on the matching; and operating, based ondetermining the position of the vehicle, the vehicle to avoid objects inthe vehicle environment.
 2. The method according to claim 1, wherein thepredefined map comprises a definition of a plurality of spatialsegments, each of the spatial segments representing a respective one ofthe plurality of parts of the map environment and being assigned to arespective one of the plurality of elements.
 3. The method according toclaim 1, wherein the matching is carried out on the basis of identifiedrespective ones of the plurality of elements and respective ones of theplurality of detection points (P) to which the identified respectiveones of the plurality of elements have been assigned.
 4. The methodaccording to claim 1, the method further comprising: determining atleast one confidence value for a respective one of the plurality ofdetection points on the basis of the spatial assignment, wherein: the atleast one confidence value represents a probability that the respectiveone of the plurality of detection points is assigned to a respective oneof the plurality of elements; and the matching is carried out on thebasis of the at least one confidence value.
 5. The method according toclaim 4, wherein the at least one confidence value is determined on thebasis of a Monte-Carlo simulation for the respective one of theplurality of detection points.
 6. The method according to claim 5,wherein the at least one confidence value is transformed to anexponential weighting factor and wherein the matching comprisesweighting by the exponential weighting factor.
 7. The method accordingto claim 1, wherein the predefined map further comprises a plurality ofdistance values representing distances between the plurality of parts ofthe map environment being assigned to the plurality of elements,respectively, wherein the distance values are used for the matching. 8.The method according to claim 1, wherein the spatial assignmentidentifies, for a respective one of the plurality of parts of the mapenvironment, a respective one of the plurality of elements having aminimum distance to the respective one of the plurality of parts of themap environment.
 9. The method according to claim 1, wherein thematching further comprises determining a rigid transformation functionby minimizing distances between transformed detection points andrespective ones of the plurality of elements being assigned to theplurality of detection points by means of the spatial assignment,wherein the transformed detection points are respective ones of theplurality of detections points transformed by means of the rigidtransformation function.
 10. The method according to claim 1, wherein atleast one element of the map comprises an extended geometrical object,in particular a line or a surface, preferably a straight line or aplane.
 11. The method according to claim 1, wherein the matching furthercomprises particle filtering.
 12. The method of claim 1, wherein: theelectromagnetic system is a radar system; and the electromagneticradiation comprises radar signals.
 13. A system comprising: at least oneradar sensor for emitting electromagnetic radiation in a vehicleenvironment and sensing the electromagnetic radiation that reflects backtowards the at least one sensor; and at least one processor configuredto: determine, based on the electromagnetic radiation received by theradar sensor, at least one scan comprising a plurality of detectionpoints (P), each detection point representing a location in the vehicleenvironment; determine, from a database, a predefined map comprising: aplurality of elements in a map environment, each of the elementsrepresenting a respective one of a plurality of static landmarks in thevehicle environment; a spatial assignment of a plurality of parts of themap environment to the plurality of elements, the plurality of partsbeing spatial positions arranged as a mesh grid comprising positions forany potential detection point; and at least a portion of the mapenvironment representing the vehicle environment; match, using thespatial assignment, the plurality of detection points (P) and theplurality of elements by at least: identifying, for a respective one ofthe plurality of detection points (P), a respective one of the pluralityof parts of the map environment, the respective one of the plurality ofparts of the map environment representing a part of the vehicleenvironment including the location represented by the respective one ofthe plurality of detection points; identifying a respective one of theplurality of elements being assigned to the identified respective one ofthe plurality of parts of the map environment; and assigning theidentified respective one of the plurality of elements to the respectiveone of the plurality of detection points (P); determine a position ofthe vehicle based on the matching, the determined position to be usedfor operating a vehicle safely in the vehicle environment.
 14. Thesystem of claim 13, further comprising the vehicle.
 15. A non-transitorycomputer-readable medium comprising instructions that, when executed,configure at least one processor to: receive, from an electromagneticsystem with at least one sensor equipped on a vehicle, electromagneticradiation emitted by the electromagnetic system and reflected in avehicle environment towards the at least one sensor; determine, based onthe electromagnetic radiation, at least one scan comprising a pluralityof detection points (P), each detection point representing a location inthe vehicle environment; determine, from a database, a predefined mapcomprising: a plurality of elements in a map environment, each of theelements representing a respective one of a plurality of staticlandmarks in the vehicle environment; a spatial assignment of aplurality of parts of the map environment to the plurality of elements,the plurality of parts being spatial positions arranged as a mesh gridcomprising positions for any potential detection point; and at least aportion of the map environment representing the vehicle environment;match, using the spatial assignment, the plurality of detection points(P) and the plurality of elements by at least: identifying, for arespective one of the plurality of detection points (P), a respectiveone of the plurality of parts of the map environment, the respective oneof the plurality of parts of the map environment representing a part ofthe vehicle environment including the location represented by therespective one of the plurality of detection points; identifying arespective one of the plurality of elements being assigned to theidentified respective one of the plurality of parts of the mapenvironment; and assigning the identified respective one of theplurality of elements to the respective one of the plurality ofdetection points (P); and determine a position of the vehicle based onthe matching, the determined position to be used for operating a vehiclesafely in the vehicle environment.
 16. The non-transitorycomputer-readable medium according to claim 15, wherein the predefinedmap comprises a definition of a plurality of spatial segments, each ofthe spatial segments representing a respective one of the plurality ofparts of the map environment and being assigned to a respective one ofthe plurality of elements.
 17. The non-transitory computer-readablemedium according to claim 15, wherein the instructions, when executed,configure the at least one processor to carry out the matching based onidentified respective ones of the plurality of elements and respectiveones of the plurality of detection points (P) to which the identifiedrespective ones of the plurality of elements have been assigned.
 18. Thenon-transitory computer-readable medium according to claim 15, whereinthe instructions, when executed, further configure the at least oneprocessor to determine the position of the vehicle by: determining atleast one confidence value for a respective one of the plurality ofdetection points on the basis of the spatial assignment, wherein the atleast one confidence value represents a probability that the respectiveone of the plurality of detection points is assigned to a respective oneof the plurality of elements, and wherein the matching is carried out onthe basis of the at least one confidence value.
 19. The non-transitorycomputer-readable medium according to claim 18, wherein theinstructions, when executed, further configure the at least oneprocessor to determine the position of the vehicle by: transforming theat least one confidence value to an exponential weighting factor; andmatching the plurality of detection points (P) and the plurality ofelements by weighting the plurality of detection points (P) and theplurality of elements by the exponential weighting factor.
 20. Thenon-transitory computer-readable medium according to claim 15, whereinthe predefined map further comprises a plurality of distance valuesrepresenting distances between the plurality of parts of the mapenvironment being assigned to the plurality of elements, respectively,wherein the instructions, when executed, further configure the at leastone processor to determine the position of the vehicle by matching usingthe plurality of distance values.